Lux
by Elaienar
Summary: Castiel loosens the collar that is constricting the neck of his vessel, but that does nothing to ease his discomfort.  He is still held in by fragile, suffocating flesh.  Spoilers up to and including 4.20.


_Disclaimer:_ Supernatural =/= mine.

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**Lux**

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It was not something he had ever done, or ever needed to do, taking a vessel, and so Castiel was unsure of what to expect as he drew his self around himself, folded his being up small and angular enough to fit inside Jimmy Novak's body. He had never experienced smallness – no, never experienced _size_; his true form might have had dimensions but they were not like these dimensions, and even if they had been, it had never mattered before. Now it did, for Jimmy Novak was tiny, fragile: incredibly finite, Uriel had told him, when he'd asked him what humans were like, and Uriel had also said that sometimes vessels would regret their choice when they felt themselves being pushed aside to make room for an angel, would feel their connection to their body being severed and would lash out in confusion and fear.

As if anything so _breakable_ could force an angel out once invited in, Uriel had said. Sometimes humans, unlike angels, had to be reminded of their promises.

Castiel had no desire to engage in a battle of wills with a human, and Jimmy Novak did not force him into one. As the angel fitted himself into the awkward corners of his vessel, its owner was already shrinking away, and so he only spoke to that flickering presence one time.

_Sleep_, he said, and Jimmy Novak slept. In the last moment before his thoughts winked out, he thought – Castiel thought – of his mother, of her gentle hands tucking him into bed, smoothing his hair back from his forehead, and turning out the light.

Jimmy Novak's mother had died when he was ten. Castiel pondered this, wondering what human emotion had caused that memory to surface at the last, but only briefly. There was work for him to do, and so he straightened, feeling the vessel stretching around him, tight in some places, loose in others, like a borrowed coat that does not quite fit.

Unlike a borrowed coat, there was nothing now to remind him of the previous owner. Perhaps, he thought, he should stitch "Jimmy Novak" into a tag set between his shoulders. But not now. Later, when there was less to do and more time to do it in.

For the time being, he drew the vessel close around him and went about his Father's business.

**o**

While Castiel was content to do his work without thought, without enjoyment or dislike, without enthusiasm or complaint, Uriel would always stop to take stock of his opponent. Know your enemy, Uriel told Castiel on more than one occasion, and Uriel always knew his enemy inside and out.

Castiel did not understand how an angel could know a demon. They were, after all, _demons_ – and before that they had been humans. There was no point of reference. On occasion he felt – not loss, but the knowledge of loss, as he burned a demon away, as one more of his Father's creations, once beautiful, now twisted beyond recognition, shone bright under his hands in that last moment before its light went out forever. Still he could not understand them, could not know the mind of a demon any more than he could know the mind of a painting or a stone statue.

But he trusted that Uriel knew, for Uriel always carefully and methodically understood his enemies.

Demons, Uriel told him, had once been human, and though hellfire had burned away every last bit of their humanity, they were still able to possess humans with an ease that angels would never attain. While angels had to ask permission of the host, demons simply slipped inside theirs, wore the ungainly limbs with grace, mimicked the expressions and emotions without difficulty. They did not remember anything, Uriel said, of being human, but false humanity came to them naturally.

Unlike angels, demons never completely subdued the soul native to the body they wore. They liked to leave a few connections intact, so that they could feel the tiny soul beating and tearing at the inside of its own skull, wanted to keep it trapped behind its own eyes, seeing, hearing, feeling, _knowing_ every hellish thing they did with its body. For a demon's vessel there was no rest, Uriel said, no deep sleep, with knowledge limited to faint scraps of memory, fast-fading like a dream. For a demon's vessel there was only a constant waking nightmare.

Uriel said that demons wanted their hosts to remember the taste of human blood in their mouths and the joy of human pain under their hands, because if the host survived being possessed, every dark memory was another step towards perdition.

Castiel listened to what Uriel said, and never thought to wonder how it was that he knew so well the demons' hatred of mankind.

**o**

To take on a new vessel would be difficult, Uriel had also said, but for Castiel there was no difficulty in using Claire Novak as a host. It was easier, in fact, than using her father: her mind was bigger than his, not yet tainted by sin or narrowed by heavy human emotions. Like her father, Claire Novak slipped away into sleep with a single word from him.

But her legs were too short and so were her arms, and the shapes her mouth made around Castiel's words were unfamiliar. Castiel experienced once again the strange sensation of being dressed in clothes that did not fit him, and wondered; he thought that he had become used to wearing mortal flesh, but perhaps he had only become used to wearing Jimmy Novak.

**o**

Inside his old vessel Castiel focuses and contracts himself until he is a mere pin-prick of light, holds himself in a strange shape just the right size so that he will not spill through the cracks and tear Jimmy Novak to pieces from the inside out. He breaths once again with Jimmy Novak's lungs and nostrils (humans look at him oddly if he does not) but inside he is a breath that is held and held and held and can never be let out.

Other angels, he knows, are less careful of their vessels. Raphael's is nothing without him, for Raphael cannot – or will not – diminish himself, and in his vessel there is not room for anything but him. Everything else was burned away when he first entered it, leaving only a thin covering of mortality, and even that cannot wholly contain him; Raphael's deadly light fills it up and still overflows.

Angels are all light and motion, but the only light in a human is the small light of the soul, hidden deep within flesh. Anna was the same when Castiel first saw her after she fell; he wondered then why Augustine had given the name "grace" to the ability to turn from natural sin, given by God to humans, while an angel's grace holds them as they are, unchanging, beings of fire and spirit, far removed from earth and the things that are of the earth.

Dust to dust, Uriel often said, as another human fell, caught between angel and demon, but Uriel is dead now; and if Adam was made of dust, Eve was made of flesh, and this one, Castiel thinks, looking down at the empty shell at his feet – another casualty of war, another human soul blackened by demon possession, until the angel's purging touch was like deadly poison – was knit together in her mother's womb, made of blood and love and a single tiny spark of light.

The spark leaves no warmth behind when it goes out: the body is already cold. Jimmy Novak's fingers are cold, too.

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_Finis_

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_A/N: So I've been thinking I should water Supernatural for ages, ever since I ran into a few interesting crossovers here. When I finally cracked (a week into NaNoWriMo no less) I ended up watching all five-and-some seasons in about three weeks. Then I sat down the instant NaNoWriMo was over and wrote this up._

_So, for the record, this came to me after four weeks of writing like an insane monkey on coffee with no sleep. If it doesn't make any sense, that is probably why._


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